The inventive concept relates to non-volatile memory devices and to methods of fabricating the same. More particularly, the inventive concept relates to vertical non-volatile memory devices including vertical strings of transistors and multiple layers of metal wiring, and to methods of fabricating the same.
The semiconductor industry employs a variety of techniques aimed at maximizing the integration of conventional planar non-volatile memory devices. These techniques include designing the structure of a cell transistor so that two or more pieces of data can be stored in a single cell of the device. Despite these techniques, the degree to which the integration of a conventional planar flash memory device can be increased is limited due to the fact that all of the wiring layers are located in a single plane (layer).
Therefore, vertical memory devices are being developed to provide higher degrees of integration. In a vertical memory device, a plurality of cell transistors of a chip are arrayed in a vertical direction